In some optical sensor devices control electrodes in a photodetector are used to demodulate photo-generated charge carriers. An electromagnetic signal, e.g. light, generated by a radiation source and amplitude-modulated by a modulation signal is directed to an object and reflected to the photodetector. A demodulation signal in-phase with the modulation signal or having a fixed phase relationship to the modulation signal is applied to the control electrodes in the photodetector. The photo-generated charge carriers are directed to a first readout node or a second readout node depending on the demodulation signal applied to the control electrodes. The photo-generated charge carriers directed to the readout nodes are detected and a phase-shift between the modulation signal and the electromagnetic signal reflected from the object and detected at the photodetector is determined. Therefore, the time of flight of the electromagnetic signal may be determined from the detected photo-generated charge carriers. In other words, mixing of the received radiation with the demodulation signal is used to determine time of flight information from the phase-shift between the radiation emitted by the radiation source and the radiation received by the optical sensor device. Thus, such optical sensor devices are also called photo-mixing devices (PMD) or demodulating detectors.
To direct the photo-generated charge carriers, control electrodes are used. In conventional sensor devices, a single kind of control electrodes is used. To be more specific, either photo-gates, or trench gates, or guide field electrodes for a current-assisted photonic demodulation, have been used.
However, the current design of optical sensor devices suffers from limitations of the quality of the sensor signal.
Therefore, an enhanced approach of converting the received electromagnetic signal into an electrical signal may be desired.